Subscriber&#39;s telephone-circuit.



A. B. SMITH. SUBSCRIBERS TELEPHONE CIRCUIT. APPLICATION FILED JULY I9. m5.

Patented Apr. 3, 1917.

. him 'lddflfhlhl l BESSEY SMlll F CHIGriG-G, ELLINOIS, A$SIGNOR T0 AUTOMATIC ELECTRIC GQMIPAIHZ', 0,. GIEHGAG-U, IIILLYN'OIS, A CORPORATION OF ILLINOIS.

.ih all whom it may 00'! score:

Be it known that ii, ARTHUR Bnssm a citizen 0' l c nited States of America, and a, ntof Chicago, county of C and o .llinoie, have invented cer new and ell improvements in. Subscrz re 'i'elepho-ne Circuits, of which the following is a spe icatiou.

My inver ion refutes r0 eubecribers teleuy phi 'ci" auite and or its principal ob jcct the iinpro ment of. the transmission. A further ob ect is rearrangement of telephone c nits embodying my improved traneiniasion scheme, in such a manner that connection Wu standard ty pes of telephone equipment near in use without; however; do parting in any way 'ircrn the principles of my invention 2o accomplish. these and other useful ends my invention comprises the means herein after set forth and claimed.

in the drawings, Figure 1 represents diagrammatically an individual line walltype no of telephone embodying the principles of my invention. Fig 2, shows a modification which is better adapted to party line service. 3, shows a further modification or rearrangement of the circuit which is so well adapted for use in connection. with a desk telephone. I 1

Referring to lfiig. l, I have. shown at 'l. a microphone transmitter which may be of any suitabletype or construction. At I s shown an. induction. coil having the windings 30 and 31 connected in a manner which will be described. phone receiver which is preferably of the non-polarized direct current type. 'At'S is 4o shown a calling device, which maybe of the general. typev of device disclosed in British patent to G. S. Dicker, No. 2965i of 1.910. It compris among other details, pair of impulse cpi'ings 13 and which may be separated a predetermined number of times through the medium of a finger hole dial (not shown), .nd a pair of shunt swings 11 and 12 which are closed whenever the finger hole dial is out of its noron coal position. At D is shown uger which may be of any suitable type at C is shown a condenser. H is'ehown a hook switch constructed that when the receiver R is placed upon the-hook the contact 10 5-5 will be closed, and when the receiver is rethe T111 wires 2 and 3 111 series with the condenser.

1. ray be readily practiced. in v battery B.

At R is shown telcbpecification of Letters Patent. Patented Apr, 3, 1917,

./ duplication filed July 19, 1915. Serial Hov 40,716. I

moved the contact 8 and the contact 9. will be closed and the contact 10 will be broken. It is evident that when the receiver is off the hook the transmitter T will be connected to the wire 2 by means of the contact 8 and the condenser C will be connected to the winding; 31 by means of the contact 9. When the receiver is hung up these connections urebroken and the condenser C is conne .l to the ringer D by the contact 10, o'er being bridged across the line The line wires 2 and 3 serve to connect the substation shown. herein to the individual line apparatus located at the central exchange. This apparatus may be of any approved central energy type, either manual or automatic, although the substation circuits shown herein are intended to be used in con junction with automatic central ofiice equipment, of which l have indicated at M an individual line switch and at N the relay windings of a connector switch through which talking battery is supplied from the The substation circuit shown in Fig. 2 is similar to the one described above except that separate condensers are provided for the ringer circuit and for the circuit of the winding 33 of the induction coil. This is done because it is necessary in party line service to adjust the capacity of the condenser C i of ringing current to which it is intended that the ringer I) shall respond. It follows therefore that the capacity-best suited to the ringer I) will not in all cases be the most efiicicntv for use in the talking circuit, hence the use of separate condensers is advisable.

In Fig.3, I have shown a circuit arrangement especially convenient for use with desk telephones. The ringer D, the induction coil 1 and the condensers C and (3* are intended to be installed together in a suitin accordance with the frequency crease the range of telephonic transmission...

liief erring to Fig. 1, the transmitter T is supplied with talking battery from the battery B over the following path: positive pole of battery, wire 3, impulse springs 13 and 1-1, receiver ll, winding 30 of induction coil 1, transmitter T, contact 8 of book switch 1-1 and wire 2 to the negative pole of battery 1). The receiver B being included in the above circuit, it has its electromannet energized and is thereby made sensitive to the alternating or fluctuating voice currents superimposed on the battery supply circuit by the charging and discharg ing of the condensers C and C during conversation. It is understood, of course, that the conductors 102 and 103 extend to another substation comp ied. with a microphone transmitter which, by varying its resistance, can produce the changing currents above mentioned.

Since the action of a transmitter in varyin; its resist-lure to produce changes in the line current is well understood we may pro-- coed without further explanation to corn sidcr in what manner my invention modifies this action.

A shunt path may be traced around the transmitter T which path extends from the upper terminal of transmitter T by way of contact 8, condenser C, contact 9, and winding 31 of induction coil I to the lower terminal of transmitter T. Considering now the transmitter T, at any given instant it will have a certain resistance resulting in a diit'erence of potential across its terminals. It follows then that the condenser G will be charged, the amount of chargedepending on the voltage across the terminals of the transmitter. Assuming now that the resistanceof the transmitter is increased the flow of cu rent in the line will be reduced. Also, owing to the increased resistance, the voltage across the transmitter terminals will be increased resulting in an increased chargeof the condenser C. The charging current liows through the winding d1 of the inductioncoil I and this winding is so connected that the charging current induces in the winding 30 ot' the induction coil :1 current which is in opposition to the main line current, thereby still further reducing it.

Taking now the case where the resistance of the transmitter is reduced, such reduction of resistance of course results in an increased fiow 01 current in the line. Also, owing to the reduced resistance, the voltage across the transmitter terminals will be reduced resultins, in a discharge of the condenser The condenser C discharges through the winding 31 of the induction coil l as before but since the discharging and charging currents are in opposite directions, the induced current in the winding 30 of the induction coil 1 is, in this case, in the proper direction to augment the current in the main line.

I am aware that this interaction between the two windings of an induction coil has ing of the induction coil and a condenser 7 forming a direct shunt circuit around the transmitter.

In Figs. 2 and 3 the operation, so far as the talking circuit and the application of the principles of my invention areconcerned, is 7 the same as in Fig. 1 and, it is believed, will be sufiiciently clear from the foregoing explanation.

To sum up, it will be seen that I have provided an efficient circuit arrangement for a substation "telephone set embracing a trans-' mitter, a winding of an induction coil and a receiver connected in series with the main circuit, and a shunt circuit around the transmitter comprising a condenser and a second winding of the induction coil, the said shunt circuit being provided for the purpose of amplifying the variations in the current flow in the main circuit caused by variations in the resistance of the transmitter.

While I have shown several embodiments of: the principles of my invention it is probable that other modifications will suggest themselves to those skilled in the art. I do not, therefore, wish to be held strictly to the forms shown herein, but desire rather to include all modifications which may come within the scope of the appended claims.

hat I claim as my invention is:

1. In a telephone system, a subscribersfioe telephone station, a line for said station, a direct current bridge across said line at said station, said bridge containing a receiver and a transmitter, a. reactive circuit for shunting said transmitter, a coil in said reactive circuit, a second coil inductively related thereto in the bridge, a condenser in said reactive circuit, another bridge circuit for said line at said station, means for substituting one bridge for the other across the line and for changing; the condenser from said re active circuit to said other bridge.

9 In a telephone system, a, subscribers telephone station, a line for said station, a direct current bridge across said line at said station, said laidge'containing a receiver and a transmitter, a reactive circuit for shunting said transmitter, a coil in said reactive circuit, a second coil inductively related thereto in the bridge, a condenser in series with said first coil. another bridge circuit for said line at said station, means for substituting one bridge for the other across the line and for changing the condenser from said reactive circuit to said other bridge.

3. in a telephone system, a. subscribers telephone station. a line for said station, a direct current bridge across said line at said station, said bridge containing a receiver and a transmitter, a reactive circuit for shunting cuit, a second coll 1 changlng the a coil in said reactive cirinductively related thereto inthe bridge, a condenser in said reactive circuit, another bridge circuit for said line at said station, means for substituting one bridge for the other across the line and for condenser from said reactive circuit to said other bridge, an automatic switch associated with said line, animpulse sender in's'eries with said transmitter for operating the switch, andasource of current controlled said transmitter,

direct current bridge across said line at said station, said bridge containing a receiver and a transmitter, a reactive circuit for shunting said transmitter, a co1l 1n sald reactive cirthrough the medium of said I switch for supplying said transmitter with cuit, a second coil inductively related thereto in the bridge, a condenser in series with said first coil, another bridge circuit for said line at said station, means for substituting one bridge for the other across the, line and'for changing the condenser from said reactive circuit to said other bridge, an automatic switch associated with said line, an impulse sender in series with said transmitter for operating the switch, and a source of current controlled through the medium of said switch for supplying said transmitter with talking current.

Signed by me at Chicago, Illinois, this 12th day of July, 1915.

ARTHUR BESSEY SMITH.

Witnesses:

CHAS. M. CANDY, W. W. OWEN.

Cook county, 

